Acheson, Jonathan

Dunne, Nicholas

Goel, Saurav

Hamilton, Andrew

Lennon, Alex

Ziminska, Monika

English

Queen's University Belfast Research Portal

Improving Mechanical Properties of Nanocomposite Coatings: Potential uses in Bone Tissue Scaffold Applications

Ulster University's Research Portal

ioengineeringBResearch GroupImproving Mechanical Properties of Nanocomposite Coatings: Potential uses in Bone Tissue Scaffold ApplicationsAcheson, J.1, Ziminska, M.1, Goel, S.2, Dunne, N.3, Hamilton, A.11School of Mechanical and Aerospace Engineering, Queen’s University Belfast, UK2School of Aerospace, Transport and Manufacturing, Cranfield University, UK3School of Mechanical and Manufacturing Engineering, Dublin City University, IrelandioengineeringBResearch Group• Tissue engineering solutions are an attractive alternative to autograft treatment for bone trauma patientsIntroductionINTRODUCTIONMATERIALS AND METHODSRESULTS CONCLUSIONS FUTURE WORK[Image] Alessandra Giuliani, Synchrotron Radiation and Nanotechnology for Stem Cell Research, Stem Cells in Clinic and Research, 2011• Bone tissue scaffold development has challenges:-• High porosity in conjunction with suitable mechanical propertiesTailor mechanical properties of bone tissue scaffolds via thin film nanocomposite coatingioengineeringBResearch GroupTunable Structure of Porous MaterialsZiminska et al. ACS Appl Mater Interfaces. 2016;8(34):21968–73.INTRODUCTIONMATERIALS AND METHODSRESULTS CONCLUSIONS FUTURE WORKPorous SubstrateCoated foamNanocomposite Coating100 µmUn-coated100 µmCoatedCoating has only been tested under ambient conditions. Testing must be done when submerged to examine efficacy under hydrated conditions“Brick-by-brick”ioengineeringBResearch GroupMaterials • Open cell polyurethane foam• Coated with varying number of quadlayers of:» Poly(ethyleneimine)» Poly(acrylic acid)» Cloisite Na+ nanoclayMethods• Tested under uniaxial compression in the elastic range at:• Under ambient conditions (≈30% RH, 21 °C)• Under DI water (100% RH, 21 °C)Hydrated Testing Materials and Methods INTRODUCTIONMATERIALS AND METHODSRESULTS CONCLUSIONS FUTURE WORK» Preload of 0.03 N » Crosshead speed of 2.0 mm/min» Deformed to 6% of strainioengineeringBResearch GroupINTRODUCTIONMATERIALS AND METHODSRESULTS CONCLUSIONS FUTURE WORKCoated Foams Hydrated TestingAverage Elastic Modulus (MPa) ± SDQuadlayers Ambient In Water In Water 1 Hour Desiccated0 0.08 ± 0.00 0.05 ± 0.00 0.05 ± 0.01 0.10 ± 0.0115 1.31 ± 0.21 0.06 ± 0.01 0.06 ± 0.01 1.08 ± 0.2730 2.78 ± 0.26 0.08 ± 0.01 0.08 ± 0.01 2.54 ± 0.3545 3.19 ± 0.28 0.07 ± 0.01 0.07 ± 0.00 3.52 ± 0.3760 4.9 ± 0.46 0.10 ± 0.01 0.09 ± 0.01 5.17 ± 0.60(n=5)01234560 15 30 45 60Elastic Modulus (MPa)Number of Deposited Quadlayers012345615 30 45 60Elastic Modulus (MPa)Number of Deposited Quadlayers45615 30 45 6Elastic Modulus (MPa)Number of Deposited QuadlayersAmbient DesiccatedCoating transitions from stiff material to material as flexible as polyurethane foamRecov ry from soft to stiff state could be utilised for actuation outside of biomaterialsLoss of mechanical properties major challenge for application in biomaterialsioengineeringBResearch GroupMechanism of Mechanical Property LossINTRODUCTIONMATERIALS AND METHODSRESULTS CONCLUSIONS FUTURE WORKProposed Solution:Water Distribution in Multilayers of Weak Polyelectrolytes[1][1] Tanchek et al. Langmuir. 2006;22(11):5137–43. ioengineeringBResearch GroupCrosslinking of Coating Design Outline INTRODUCTIONMATERIALS AND METHODSRESULTS CONCLUSIONS FUTURE WORKTwo-level factorial design of experiments (DoE) to investigate crosslinking effectInputs:• Glutaraldehyde molarity (M) 0.00 - 2.50 M• Glutaraldehyde time (mins) 30 - 300 mins• Thermal treatment temperature (°C) 0 or 120 °C• Thermal treatment time (mins) 60 - 1500 mins• Crosslink treatment interval 5 or 30 quadlayersOutputs:• Ambient elastic modulus (kPa)• Hydrated elastic modulus (kPa)• Coating thickness (µm)ioengineeringBResearch GroupCrosslinked Coated Foams Hydrated TestingINTRODUCTIONMATERIALS AND METHODSRESULTS CONCLUSIONS FUTURE WORK050010001500200025000.00 0.50 1.00 1.50 2.00 2.50Hydrated Elastic Modulus (kPa)Glutaraldehyde Molarity (M)DOE Input CorrelationGlutaraldehyde Molarity (M)0.577Glutaraldehyde Time (mins)-0.012Temperature (°C) -0.117Temperature Time (mins)-0.215Crosslink Interval -0.374 05010150202505 10 5 20 25 30Hydrated Elastic ModulusCrosslink Interval05001000150020002500300035004000450050000 15 30 45 60 60 60Elastic Modulus (kPa)Number of Deposited QuadlayersAmbientHydratedNot CrosslinkedCrosslinkedA: Glutaraldehyde MolarityB: Glutaraldehyd  TimeC: TemperatureD: Temperature TimeE: Crosslink IntervalPositive EffectsNegative EffectsioengineeringBResearch Group• Mechanical contribution of (PEI/PAA/PEI/Nanoclay) coating is negligible upon submersion in DI water• Mechanical properties of coating fully recover to match elastic modulus under ambient conditions, after desiccation• Effects of hydration on coating analogous with water plasticisation as described by Tanchak et al.[1]• Chemical crosslinking of primary amine groups between PEI layers is the main factor for retention of mechanical properties when hydrated» Effect of thermal temperature» Effect of thermal time» Effect of glutaraldehyde time• Crosslinking improved retention of elastic modulus in water by up to 45%, further improvements expected after DoE optimisationConclusionsINTRODUCTIONMATERIALS AND METHODSRESULTS CONCLUSIONS FUTURE WORK[1] Tanchek et al. Langmuir. 2006;22(11):5137–43. Not significant» Effect of glutaraldehyde molarity» Crosslink pointSignificantioengineeringBResearch Group• Optimised crosslinking experiment based on DoE analysis» Confirmation and validation of DoE analysis» Confirmation of crosslinking activity• Compile results  alongside Ziminska et al. Ashby-Gibson model adaptation » Predict potential hydrated elastic modulusFuture WorkINTRODUCTIONMATERIALS AND METHODSRESULTS CONCLUSIONS FUTURE WORKioengineeringBResearch GroupAcknowledgementsSpecial ThanksDr. A HamiltonM. ZiminskaProf. N DunneDr. S GoelDr. A LennonBioengineering Research GroupDEL Funding 

Improving mechanical properties of nanocomposite coatings: potential uses in bone tissue scaffold applications

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Improving mechanical properties of nanocomposite coatings: potential uses in bone tissue scaffold applications

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